• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1108-1117
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• 2005

RAP(rammed aggregate pier) method which is intermediate foundation of deep and shallow foundation is used to improve the ground with high compaction energy. This method is widely spread around the world, but there are few examples and systemic researches for failure mechanism and bearing capacity of this method are not organized yet. In this paper, soil laboratory tests were carried out to evaluate the applicability of RAP method as the foundation of a structure. And the bearing capacity and the failure mechanism of RAP method were studied with respect to various relative densities(35%, 65%, 90%), diameters(45mm, 60mm) and lengths(20cm, 30cm, 40cm). As results, stress concentration ratio decreased as diameter of RAP was increasing or length of RAP was decreased or relative density was decreased. however these results were not always constant. because systematic interaction between relative density and diameter and length of RAP can affect stress concentration ratio, more studies on stress concentration ratio are needed throughout laboratory and field tests.

• 대한기계학회논문집
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• 제8권2호
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• pp.111-118
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• 1984

본 연구에서는 상계해 이론으로부터 마찰 상수 m에 대한 해석을 시도하여 조 직의 치밀화, 링의 내경감소율 등의 소결금속에 대한 성형특성을 여러가지 상대밀도, 마찰상수에 대해서 계산했다. 실험은 철 분말 소결금속인 시편을 상대밀도가 0.75, 0.85, 0.9이고 링의 외경:내경:높이의 비가 6:3:1과 6:3.1:1.5로 제작했고, 평 금형 (parallel platens) 사이에서 여러가지 윤활상태로 시행하여 그 실험치와 이론치들을 비교 하였다.

• 한국지반신소재학회논문집
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• 제12권4호
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• pp.87-98
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• 2013

본 연구는 석탄회의 상대밀도를 40%, 60%, 80%, 95%로 각각 변화시켜 등방압축팽창시험과 구속압력을 달리한 배수삼축시험을 하였다. 그리고 이 시험자료를 이용하여 Lade의 단일항복면 구성모델의 토질매개변수의 변화 특성을 알아보았다. 그 결과 탄성성분을 나타내는 토질매개변수 Kur과 n은 상대밀도의 변화에 따른 영향이 미소하고 파괴규준, 경화함수, 소성포텐셜에 관련된 토질매개변수는 상대밀도의 증가에 따라 선형적인 증 감현상을 보이고 있다. 그리고 항복함수에 관련된 토질매개변수 h와 ${\alpha}$는 상대밀도에 따른 변화가 미세하고 파괴규준에 관련한 토질매개변수와 관련성이 매우 높아 파괴규준, ${\eta}_1$에 관한 식으로 대체할 수 있으며, 이 식을 이용하여 수치해석한 결과 양호하게 예측하고 있다.

• Journal of Pharmaceutical Investigation
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• 제38권1호
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• pp.1-8
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• 2008

Planetary ball mill was used to decrease and control the particle size of excipients. The effects of the weight of sample and the revolution number of mill, and grinding time on the particle size of the ground sample were analyzed by response surface methodology. The optimum conditions for the milling of microcrystalline cellulose were 38.82 g of the weight of sample and 259 rpm of the revolution number of mill, and 45 minutes of grinding time. The predicted value of the particle size at the these conditions was $19.02{\mu}m$, of which the experimental value at the similar conditions was $18.68{\mu}m$. The tensile strength of tablets of single-component powders, such as microcrystalline cellulose, hydroxypropylmethyl cellulose and starch, binary mixtures and ground binary mixtures of these powder were measured at various relative densities. It was found that the logarithm of the tensile strength of the tablets was proportional to the relative density. A simple model, based upon Ryshkewitch-Duckworth equation that was originally proposed for porous materials, has been developed in order to predict the relationship between the tensile strength and relative density of ground binary tablets based on the properties of the constituent single-component powders. The validity of the model has been verified with experimental results for ground binary mixtures. It has demonstrated that this model can well predict the tensile strength of ground binary mixtures based upon the properties of single-component powders, such as true density, and the compositions. When the tensile strength of the mixture of microcrystalline cellulose hydroxypropylmethyl cellulose (90:10) and the ground mixture of them were compared, the tensile strength of the ground mixture decreased widely from 45.3 to 5.6% compared to the mixture in case the relative density of tablets was in the range of $0.7{\sim}0.9$. When the tensile strength of the mixture of microcrystalline cellulose starch (80:20) and the ground mixture of them were compared, the tensile strength of the ground mixture decreased widely from 31.0 to 11.6% compared to the mixture in case the relative density of tablets was in the range of $0.7{\sim}0.9$.

• 대한토목학회논문집
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• 제31권1C호
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• pp.11-17
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• 2011

본 연구는 백마강 모래의 상대밀도를 25%, 50%, 80%, 100%로 각각 변화시켜 등방압축-팽창시험과 구속압력을 달리한 일련의 배수삼축시험을 하였다. 그리고 이 시험자료를 이용하여 회귀분석을 근거로 상대밀도의 변화에 따른 Lade의 단일항복면 구성모델의 토질매개변수의 변화 특성을 알아보았다. 그 결과 탄성성분을 나타내는 토질매개변수 Kur과 n은 상대밀도의 변화에 따른 영향이 미소하고 파괴규준, 경화함수, 소성포텐셜에 관련된 토질매개변수는 상대밀도의 증가에 따라 선형적인 증 감현상을 보이고 있다. 그리고 항복함수에 관련된 토질매개변수 h와 ${\alpha}$는 상대밀도에 따른 변화가 미세하고 파괴규준에 관련한 토질매개변수와 관련성이 매우 높아 파괴규준, ${\eta}_1$에 관한 식으로 대체할 수 있으며, 이 식을 이용하여 수치해석 한 결과 양호하게 예측하고 있다.

• 한국분말재료학회지
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• 제5권4호
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• pp.279-285
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• 1998

The microstructures and mechanical properties of submicron WC-Co cemented carbides were investigated in relation to cobalt content. To inhibit the WC grain growth during sintering, VC was added as a inhibitor in each alloy with 3 mass% to the cobalt content. The WC-(5, 8, 10, 15, 20) mass% Co compacts were sintered at $1400^{\circ}C$ for 30 min in vacuum. Some of WC-(5, 8, 10) mass% Co sintered compacts were HIPed with 120 atm at 130$0^{\circ}C$ for 1 hr. The shrinkages of all HIPed alloys were increased without depending on the cobalt contents and the sintered densities of them. The relative densities of the alloys were increased with the cobalt content and HIPing. The less the cobalt content, the larger the WC grain. Many contiguities of WC grains were found in WC-5 mass% Co alloy. The sizes and numbers of pores in the alloys were decreased by HIPing. And also the strength and the hardness of each alloy were increased. The maximum hardness was about 18.95 GPa in the WC-5 mass% Co alloy HIPed and the maximum transverse-rupture strength (T.R.S.) 3.2 GPa in the WC-20 mass% Co alloy sintered.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.437-438
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• 2007

In this paper a embedded decoupling capacitor design with gap structure will be discussed. A novel structure is modeling and analization by High Frequency Structure Simulator (HFSS). Proposed capacitor have $2m{\times}2m$ in rectangular shape. The film thickness of copper/dielectric film/substrate is respectively 35um/20um/35um. A dielectric layer of BaTiO3/epoxy has the relative permittivity of 25. Compare of the planar decoupling capacitor, capacitance densities of this structure in the range of $55{\mu}F$/mm2 have been obtained with 50um gap while capacitance densities of planar structure $55{\mu}F$/mm2 in the same size. The frequency dependent behavior of capacitors is numerically extracted over a wide frequency bandwidth 500MHz-7GHz. The decoupling capacitor can work at high frequency band increasing the gap size.

• 대한금속재료학회지
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• 제49권8호
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• pp.601-607
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• 2011

The study investigated the influence of current density on the corrosion-protection properties of an AZ91 Mg alloy subjected to plasma electrolytic oxidation coating. The present coatings were carried out under an AC condition at three different current densities, i.e., 100, 150, and $200mA/cm^2$. From microstructural observations, the micro cracks connecting each micro pore were pronounced on the oxide surface of the samples coated at current densities higher than $150mA/cm^2$ since increasing the current density in this study led to an increment in the relative volume fraction of the MgO compound. Based on potentio dynamic polarization and immersion tests, the sample coated at a current density of $100mA/cm^2$ showed superior corrosion resistance.

• 천문학회지
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• 제26권1호
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• pp.73-78
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• 1993

We have mapped the $C_3H_2\;2_{12}-1_{01}$ transition line toward the Sgr A molecular cloud on a 1' grid spacing and derived $C_3H_2$ column densities of $3\~7\times10^{14}\;cm^{-2}$ for molecular clouds of Sgr A. The fractional abundances of $C_3H_2$ relative to $H_2$ are obtained to be $3\~6\times10^{-9}$, which are slightly lower than that for the cold dark cloud TMC-1 but are enhanced by factors of 5-60 compared to those for Sgr B2 and the Orion extended ridge. We also estimate from the $C_3H_2$ column densities total masses of $\~10^6\; M_\bigodot$ for two clouds (M - 0.13 - 0.08 and M - 0.02 - 0.07), which are thought to be close to the virial equilibrium. We suggest that the large abundance of $C_3H_2$ in Sgr A may be partly due to the activities of the Galactic center.

• 한국응용곤충학회지
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• 제34권4호
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• pp.391-405
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• 1995

수원 지방에 서식하는 바퀴의 종류와 상대밀도를 조사하기 위하여 수원 시내 7개 다른 서식처, 여관, 다방, 중식 음식점, 한식 음식점, 개인 병원, 아파트, 그리고 단독주택을 선정하여 끈끈이 트랩에 의한 바퀴의 채집과 서식처별 상대밀도조사를 1994년 2월부터 11월까지 실시하였다. 설치된 3,039개의 트랩 중 1,435개의 트랩에서 한마리 이상의 바퀴가 채집된 Positive Trap Rate(양성 트랩율)은 47.22%였다. 중식 음식점에서의 양성트랩율은 72.67%이었고, 채집된 바퀴의 수가 전 채집개체의 48.84%로 바퀴오염이 가장 심한 빈도를 나타내었다. 그에 비하여 한식 음식점, 아파트, 단독주택, 다방, 여관, 그리고 병원에서는 보다 조금 낮거나 매우 낮은 60.6%, 58.61%, 52.22%, 38.67%, 24.88% 그리고 17.54%로 각각 나타났다. B. germanica는 전 채집개체 수의 97.36%로 가장 높은 밀도를 나타내었으며, 55.01 개체/트랩/주의 평균 밀도를 보였다. 반면, 다른 종인 P. japonica, P. americana와 P. fuliginosa는 이보다 훨씬 낮은 2.35%, 0.14%, 0.14%를 보였다. 7개의 서로 다른 서식처에서 개체군 밀도를 조사해 본 결과 중식 음식점과 한식 음식점에서 20.56과 8.31개체/트랩/주라는 보다 높은 개체군 밀도가 관찰되었다. 그에 비해 아파트, 다방과 단독주택에서는 5.33, 3.79와 3.53 개체/트랩/주의 중간 범위 밀도가 조사되었고, 비교적 낮은 밀도가 병원(0.18 개체/트랩.주)과 여관(1.00 개체/트랩/주)으로 부터 관찰되었다.